This invention concerns aqueous solutions of polyoxyalkylene, di, tri or tetra amines substituted at the amine position with a polymethylene sulfonate group such as polyoxypropylene diamine N-N'-dipolymethylene sulfonate, which may be used to carry in aqueous solution other constituents reactable with the amino and/or hydroxy substituent of the polymethylene sulfonate substituted polyoxyalkylene amine to produce hydrophilic high molecular weight polymers. Such solutions are useful for stabilizing soil permeability and sealing subterranean zones, such as a permeable earth formation that is penetrated by a well bore for the production of crude oil.
The necessity for decreasing the permeability of or consolidating various subterranean formations, such as loose or unconsolidated reservoir sands, has long been known. Several processes have been proposed for doing so by injecting pumpable fluids into such formations which, when in place, polymerize or otherwise react to become highly viscous and act as a flow-resistant gel. The need often arises in the drilling for oil wherein water enters the bore hole from water-bearing formations and interferes with the drilling operation.
Examples of such gel forming fluids may be found in U.S. Pat. No. 3,195,630 describing aqueous solutions of urea and metal salts which react to form a gel, U.S. Pat. No. 3,308,884 describing epoxy amino resin-forming constituents with aromatic solvents that become flow-resistant gels, and U.S. Pat. No. 3,324,041 describing an emulsion of asphalt, polyamides and polyepoxy polymers that set to form materials of high viscosity. However, such gel-forming processes cannot always be successfully employed. In unconsolidated reservoir sands the portions of the sand plugged by the gel are often displaced into the well. In other formations wherein permeability is relatively low at the outset, such gelling emulsions are often too viscous to satisfactorily penetrate into the reservoir.
Other processes have been proposed that plug loose sands by converting them to consolidated, compression-resistant plugs. However, such processes tend to be undesirably or prohibitively expensive in many situations.
Pumpable epoxy-resin compositions for sealing subterranean zones have been proposed. U.S. Pat. No. 3,933,204 describes an aqueous emulsion which contains an epoxy-resin forming polyepoxy polymer, an acrylic-resin forming polycarboxy polymer and a polymerization rate controlling substance that causes the emulsion to set to a resinous plug after implacement in a formation. U.S. Pat. No. 3,960,801 describes an epoxy-resin composition for sealing a subterranean zone about a well bore, which composition contains a select aromatic diluent and curing agent that sets to an impermeable matrix closing access to the zone from the well bore.
So far as is presently known, there has not yet been proposed an epoxy-resin composition for sealing subterranean formations that employs a polyoxypropylene polyamine as the curing agent. Polyoxypropylene polyamines, such as illustrated and described in U.S. Pat. Nos. 3,236,895 and 3,462,393 are known to be excellent curing agents that impart highly desirable mechanical properties to a cured epoxy-resin, which properties would also be desirable when an epoxy composition is employed to alter the permeability of or plug a formation. Further, such polyoxypropylene polyamines generally have low viscosities and produce resins with low initial viscosities, a highly desirable property wherein the resin is to be injected into a permeable formation prior to curing. However, polyoxypropylene polyamines have not been employed as the curing agent for an aqueous epoxy-resin composition designed for injection into the subterranean formation because of the poor dispersion charcteristics of such components when placed in water solutions. The primary drawback is that the epoxy resin is not readily soluble in a water carrier, hence at best it only forms an emulsion that is difficult to inject. Although the polyoxypropylene polyamine is readily water soluble, it does not assist the solubility or dispersibility of the epoxy component. Therefore, although an amine-epoxy-water system would appear to be desirable, heretofore such systems were not practical due to the difficulty of injecting such formulation into the formation.
It has now been discovered that a polyoxypropylene polyamine may be chemically modified to make it suitable as an aqueous dispersing curing agent for epoxy-resin compositions and that when so modified it will still impart to the cured-in-place resin many of the desirable physical properties normally associated with resins cured by unmodified polyoxypropylene polyamine curing agents. The chemical modification to the amine renders it capable of making the epoxy component readily soluble or finely dispersible in aqueous solutions, hence producing a curable aqueous epoxy-resin solution that is readily injectable into underground formation.